June 20, 2014 No. 2014-15

Dr. Jarrod Hardke, Dr. Gus Lorenz, Dr. Bob Scott, & Dr. Yeshi Wamishe

Crop Progress

“How high’s the water, papa?”

We don’t have all the rice flooded yet, but it hasn’t been for a lack of effort. After all the rain received the first part of the month, it certainly got hot and dry in a hurry. Flooded rice is burning through water as fast as it can get it.

Across the state the rice crop really appears to be in great shape. Where we don’t have drift, tank contamination, carryover, etc., it’s pretty impressive looking actually. I hope I get to keep saying that all year long.

Acreage Projections: Updated acreage estimates are due out June 30. It looks like we easily have 1.4 million acres but hitting the March estimate of 1.5 million acres seems more likely. Rice is everywhere. The medium-grain acreage is probably greater than previously projected, likely coming in somewhere over 200,000 acres.

Yield Projections: What sort of shape might we find ourselves in come harvest? Tough to say – a lot of it will depend on just how diligent folks were in getting nitrogen out and weeds under control. It was a tall order but it looks like we did well so far. I’m not predicting a new state average yield record this year, but I would like to be proven wrong on that. I would also like to avoid making predictions, but people keep asking so there’s the answer I’ve been giving.

This week over 90% of rice in the state should be fertilized and flooded. t on purpose. We’re now seeding acreage beginning to move fully into internode elongation (Table 1). As expected with the cooler, rainy weather of the past couple of weeks, some of the acreage is taking longer to reach this stage. The first rice in the state to start heading is projected to do so in just two weeks (Table 2).

Table 1. Percent of rice acres set to reach internode elongation during listed weeks of 2014 according to DD50 enrollment.

Internode Date

Percent

Reached IE

35%

June 22-28

41%

June 29 – July 5

19%

July 6-12

4%

July 13-19

1%

July 20-26

0%

Table 2. Percent of rice acres set to reach 50% heading during listed weeks of 2014 according to DD50 enrollment.

Heading Date

Percent

July 5-11

7%

July 12-18

38%

July 19-25

40%

July 26 – Aug 1

11%

Aug 2-8

3%

Aug 9-15

1%

Out Standing in Your Field

Herbicide Injury

Pin the tail on the herbicide problem has been the game of the week. Chances are one of us has been in a field near you this week that has an herbicide issue. Odds are it was drift.

Liberty (glufosinate) drift has been a common sight (Picture 1). Note the spots with water-soaked edges on the leaves. This is typical Liberty drift symptomology. By and large, this injury is purely cosmetic and no yield losses will be associated with Liberty drift. You don’t like to see it, but the rice will be fine.

Picture 1. Liberty drift on rice.

Newpath (imazethapyr) drift has also been a frequent complaint. Plenty of cultivars have been hit, but we’re seeing interesting things when we’ve run into Newpath drift on Mermentau – namely the presence of Clearfield off-types (Pictures 2, 3). We don’t want to see these off-types but they do help in diagnosing Newpath drift compared to other herbicides.

In Picture 4, there is drift from an adjacent corn field. A combination of Roundup + Atrazine + Warrant was applied to the corn and made its way across nearly half of the rice field. In the same area, Roundup + Prefix was drifted from soybean onto a number of rice fields.

Picture 4. Roundup + Atrazine + Warrant drift on rice.

Disease Update

So far there have been no reports of major rice disease in Arkansas except a few cases of seedling problems largely caused by Pythium. However, damage from herbicides together with the cold, wet spring were tough on rice seedlings giving them ill-appearance.

Blast has been reported for the first time this year in Louisiana. There have been no other reports of blast from the rice-growing states in the Mid-South. If conditions are favorable, blast is a can spread very fast and with severe neck blast (Picture 5) it can cause dramatic yield loss up to 100 percent. The source of inoculum for blast disease could be from residue, seeds, or spores carried by the wind. Since leaf blast symptoms (Picture 6) can be confusing, accurate scouting and diagnosis is required. Any blast history is a good indicator of potential disease problems. Therefore, fields with history planted to susceptible cultivars need to be monitored regularly. An integrated approach of flood depth and timely protective fungicide application provide adequate blast control. Leaf blast earlier in the season can be managed with a deep flood. Additional management using fungicides may be needed for leaf blast in susceptible cultivars in blast-prone fields. The latest timing of fungicide application for neck blast is when heads are 50-75% out of the boot. Fungicides applied later than the recommended timing will not be effective.

Picture 5. Neck blast blanks rice panicles.

Picture 6. Severe leaf blast dries rice leaves.

Sheath blight (Picture 7) has also been reported in Louisiana in several fields and across cultivars. In Arkansas sheath blight usually starts to appear a few weeks after flooding. Scouting for sheath blight and applying fungicides only when thresholds are met will pay off by reducing the risk of fungicide resistance and unnecessary costs. Fungicide applications are not needed “just to protect the rice” or just because sheath blight is present. The disease has to get to the threshold level for a fungicide application to be worthwhile.

Picture 7. CL151 artificially inoculated with sheath blight fungus.

Autumn decline or black root rot caused by hydrogen sulfide toxicity may start as early as two weeks after flooding. This phenomenon can be tricky and substantial yield loss may occur unless timely action is taken to “drain and dry” to allow oxygen into the soil. Fields with history or suspicious fields need regular scouting. When scouting, compare rice roots from the bar ditches or deeper flood areas in the field with roots from the levees. Roots from the levees usually appear normal. When black roots are exposed to air, the black color fades away slowly – indicating air as the possible cure. That is why the “drain and dry” strategy is recommended. In worse situations lower leaves start yellowing and eventually die, often causing a yellow cast in the field when observed from a distance (Picture 8). Do not wait until the lower leaf symptoms get worse. A preventative approach is better than rescue strategy.

Picture 8. Rice field affected by autumn decline with lower leaves dying shows a yellow cast from a distance.

Deficiencies

Nutrient deficiencies haven’t been widespread but there have been a few cases showing classic symptomology. In Picture 9 is zinc deficiency with bronzing of lower leaves and a bright midrib. In Picture 10 is brown spot disease possibly caused by potassium deficiency.

Picture 9. Zinc deficient rice.

Picture 10. Brown spot on rice suggesting potassium deficiency.

Insect Update

Rice water weevils remain very active (Picture 11) these days and leaf scarring is likely very obvious. If you’re over 35-40 days after planting then you can’t always depend on insecticide seed treatments to protect you. Options are to time an insecticide application to control adults before they lay eggs – application timing should be 5-7 days after establishing the permanent flood. If that window is missed and RWW pressure is heavy, then the only option left is to drain fields until the soil cracks.

Picture 11. Rice water weevil adult about to feed on a rice leaf.

Growers keep track of their flood depths using any means available to them. I’ve seen a number of different gauges for doing this, but the one in Picture 12 is one of the better ones I’ve run across.

Picture 12. Flood depth gauge for monitoring rice water.

DD50 Enrollment

Some changes have been made to the online DD50 Program this year. Hopefully these and future changes will continue to make the program easier and more efficient to use. If you have any questions, or suggestions for improving the program, please let us know. You can access the online program here: http://DD50.uaex.edu/.

Additional Information

Arkansas Rice Updates are published periodically to provide timely information and recommendations for rice production in Arkansas. If you would like to be added to this email list, please send your request to jhardke@uaex.edu.

This information will also be posted to the Arkansas Row Crops where additional information from Extension specialists can be found. Please visit the blog at http://www.arkansas-crops.com/

Acknowledgements

We sincerely appreciate the support for this publication provided by the rice farmers of Arkansas and administered by the Arkansas Rice Research and Promotion Board.

The authors greatly appreciate the feedback and contributions of all growers, county agents, consultants, and rice industry stakeholders.